In the planning of the class AB output stages, such as those used in operational power amplifiers, it is sought to attain the following characteristics:
high linearity, that is, low harmonic distortion; PA1 low distortion owing to the switching between one final power component and the other; PA1 high ratio between maximum output current and rest current; PA1 substantial independence of the rest current from the temperature and from variations in the manufacturing parameters if it is produced in an integrated circuit; and PA1 circuit simplicity.
Various class AB output amplifier stages with complementary MOSFET transistors are known which permit one or some of the above characteristics to be attained, but none of them is able to obtain all of them, as would be desirable.